engleski

Solid-state Suzuki-Miyaura cross-coupling reactions catalyzed by dimeric monopalladated azobenzenes

Formation of CC bond via metal-catalyzed cross- coupling reactions, such as Suzuki-Miyaura, Sonogashira, and Mizoroki-Heck reactions, remains of interest to organic chemists. With chemistry shifting to designing new synthetic routes and protocols following a more sustainable and environmentally friendly approach, solid-state reactions have gained more traction. The benefits of this approach are numerous, ranging from a broader reactants scope to the almost total omission of solvents in a chemical reaction. Although solid-state methodologies provide access to a wide array of new products that are sometimes unattainable in solvent-based reactions, detailed insight into the reaction mechanisms and the role of metal catalysts in these transformations are still unexplored. Here we report the palladium(II)-catalyzed solid-state reactions of 4-halo-substituted azobenzene with phenylboronic acid as an arylating agent. Various phosphine-free dimeric monopalladated complexes of azobenzenes with different bridging ligands were synthesized, and their potential as catalysts in these reactions was studied. To gain insight into the mechanism of such processes, all reactions were monitored in situ by Raman spectroscopy. Results of Raman monitoring were compared with those obtained for the analogous reactions catalyzed commercially available Pd(II) catalysts.

mechanochemistry ; catalysis ; Suzuki-Miyaura reaction ; palladium

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